package servlet;

import pojo.User;

import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;
import java.sql.*;
import java.util.ArrayList;
import java.util.List;

@WebServlet(urlPatterns ={"/user"})
public class UserServlet extends HttpServlet {
    //alt +insert
    @Override
    protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        doPost(req, resp);
    }

    @Override
    protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        List<User>users=new ArrayList<>();
            // 1、加载驱动
            try {
                Class.forName("com.mysql.cj.jdbc.Driver");

                // 2、获取连接 (url username password)
                String url = "jdbc:mysql://127.0.0.1:3306/jdbc?characterEncoding=utf-8";
                Connection connection = DriverManager.getConnection(url, "root", "Zyk20040710.");
//            if (connection != null) {
//                System.out.println("连接成功");
//            }
                // 3、写sql
                String sql = "select * from user";

                // 4、预编译sql
                PreparedStatement preparedStatement = connection.prepareStatement(sql);

                // 5、有参数设置参数

                // 6、执行sql
                ResultSet resultSet = preparedStatement.executeQuery();

                // 7、遍历结果集
                while (resultSet.next()) {
                    User user = new User();
                    user.setId(resultSet.getInt(1));
                    user.setName(resultSet.getString(2));
                    user.setPass(resultSet.getString(3));
                    //把对象添加到集合中
                    user.add(user);
                }

                // 8、关闭资源
                resultSet.close();
                preparedStatement.close();
                connection.close();
                //把集合中数据存储到作用域中
                req.setAttribute("users",users);


            } catch (ClassNotFoundException e) {
                throw new RuntimeException(e);
            } catch (SQLException e) {
                throw new RuntimeException(e);
            }
        }

    }
